CN113528813A

CN113528813A - Preparation method of iron powder and vanadium-rich titanium material

Info

Publication number: CN113528813A
Application number: CN202110891803.0A
Authority: CN
Inventors: 黄琦欢; 冉杰; 阳光; 阳莉; 王怀永
Original assignee: Panzhihua Jinyuan Technology Co ltd
Current assignee: Panzhihua Jinyuan Technology Co ltd
Priority date: 2021-08-04
Filing date: 2021-08-04
Publication date: 2021-10-22

Abstract

The invention discloses a preparation method of iron powder and a vanadium-rich titanium material, which comprises the following steps: mixing the vanadium-titanium-iron ore concentrate with a reducing agent, a catalyst and a binder uniformly to obtain a raw material; carrying out microwave heating reduction on the raw material to obtain a raw material subjected to microwave heating reduction; performing water quenching on the raw material subjected to microwave heating reduction to obtain a water-quenched material; and (3) carrying out ore grinding-ore dressing on the water-quenched material to obtain iron powder and a vanadium-rich titanium material. The method can effectively separate iron and titanium components, improve metallization rate, reduce process energy consumption and reduce industrial production cost.

Description

Preparation method of iron powder and vanadium-rich titanium material

Technical Field

The invention relates to the technical field of mineral processing, in particular to a preparation method of iron powder and a vanadium-rich titanium material.

Background

In the field of iron powder production for powder metallurgy, high-grade iron ore concentrate (TFe 68-70%) is generally reduced by coal-based gas to obtain primary reduced iron powder abroad, the main reduction equipment is a rotary kiln or a tunnel kiln, and the heating mode is coal, gas or heavy oil. In China, because high-quality iron ore concentrate and natural gas or heavy oil are lacked, iron scale (steel rolling iron scale) is mostly used as a raw material, blast furnace gas of an iron and steel plant is used as fuel gas for heating, and coal powder or coke powder is used as a reducing agent to react in a tunnel kiln to obtain primary reduced iron powder. This method is most prevalent with the foreign haggans method, but its drawbacks are also evident: firstly, the iron ore concentrate with high grade hardly exists in China, the iron scale has to be selected as a raw material, but the source of the iron ore concentrate is complex, so that the component fluctuation is large, and the impurity content is high; secondly, natural gas and heavy oil resources in China are deficient, blast furnace gas or coke oven gas is forced to be selected as a heat source, and a factory needs to be established in combination with a steel enterprise, so that the cost is high; thirdly, the gas heating is mainly a radiation and heat conduction heating mode, the heat efficiency is low, the temperature rise in the tunnel kiln is slow, the temperature distribution uniformity is poor, the production period reaches dozens of hours, and the production efficiency is severely restricted. At present, tens of thousands of tons of high-end iron powder needs to be imported to domestic powder metallurgy plants every year in China, the price of the high-end iron powder is twice of that of domestic like products, and a large amount of work can be done in the aspect of improving the quality of the iron powder.

Since the 80 s of the last century, microwave heating carbon reduction iron ore concentrates, particularly complex symbiotic iron ore concentrates, are researched at home and abroad, but are limited by factors such as too small microwave source power, unadjustable power, short service life and the like, and are mostly limited in the research range of laboratories; in recent decade, with the progress of microwave heating equipment, microwave heating is gradually transferred from low-temperature drying to high-temperature reduction or oxidation processing of refractory minerals, but at present, microwave heating is mostly used for improving the problem of energy consumption in the ore grinding process, most of microwave heating is still laboratory tests, and there are few reports of practical industrial production, especially in Panxi area, a production line for separating iron and titanium after microwave heating reduction by using vanadium titano-magnetite as a raw material is blank.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a preparation method of iron powder and a vanadium-rich titanium material, which can effectively separate iron and titanium components, improve metallization rate, reduce process energy consumption and reduce industrial production cost.

In order to solve the problems provided above, the technical scheme adopted by the invention is as follows:

the invention provides a preparation method of iron powder and a vanadium-rich titanium material, which comprises the following steps:

mixing the vanadium-titanium-iron ore concentrate with a reducing agent, a catalyst and a binder uniformly to obtain a raw material;

carrying out microwave heating reduction on the raw material to obtain a raw material subjected to microwave heating reduction;

performing water quenching on the raw material subjected to microwave heating reduction to obtain a water-quenched material;

and (3) carrying out ore grinding-ore dressing on the water-quenched material to obtain iron powder and a vanadium-rich titanium material.

Preferably, the vanadium-titanium-iron ore concentrate is uniformly mixed with a reducing agent, a catalyst and a binder, and then briquetting and drying are carried out.

More preferably, the briquetting and drying treatment specifically comprises the following steps: pressing the honeycomb briquette into briquettes with the shape of honeycomb briquette by using a briquetting machine, wherein the height of each briquette is 65mm, the diameter of each briquette is 90mm, 9 through holes with the diameter of 10mm are arranged, each briquette is 710-720 g in weight, and the briquettes are dried by exposure to the sun for 3 days so that the moisture content is less than 0.8%.

Preferably, the vanadium-titanium-iron ore concentrate comprises the following components in percentage by mass:

TFe 50％～60％，FeO 18～28％，TiO₂ 9.5～20％，V₂O₅ 0.5～0.8％，CaO 0.4～1.5％，SiO₂ 3.5～5.5％，MgO 0.6～4.0％，Al₂O₃ 1.0～5.0％，S 0.5～1.2％。

more preferably, the vanadium-titanium-iron ore concentrate comprises the following components in percentage by mass: TFe 59.50%, FeO 24.90%, TiO₂ 9.60％，V₂O₅ 0.69％，CaO 0.41％，SiO₂ 4.11％，MgO 0.84％，Al₂O₃ 1.23％，S 0.75％。

Preferably, the percentage content of the vanadium-titanium-iron ore concentrate with the granularity of-200 meshes accounts for more than 80% of the total mass.

Preferably, the reducing agent is a carbonaceous reducing agent.

Preferably, the percentage content of the reducing agent with the granularity of-200 meshes accounts for more than 60% of the total mass.

More preferably, the carbonaceous reducing agent is coal dust, and the coal dust comprises the following components in percentage by mass: 85.15% of C, 7.08% of A, 7.47% of V and 0.27% of S.

Preferably, the catalyst is a mixture of sodium sulfate and sodium chloride.

Preferably, the binder is corn starch.

Preferably, the raw materials comprise, by mass, vanadium-titanium-iron ore concentrate: reducing agent: catalyst: binder (76.0-79.5): (16-19): (2.1-4.5): (0.8-0.9)

More preferably, the raw materials comprise, by mass, vanadium-titanium-iron ore concentrate: coal powder: sodium sulfate: sodium chloride: corn starch ═ 76.0-79.5: (16-19): (1.0-2.2): (1.1-2.3): (0.8-0.9).

Preferably, the frequency of the microwave source in the microwave heating reduction process is 2450 MHz.

Preferably, the temperature for microwave heating reduction is 1080-1300 ℃.

More preferably, the temperature for microwave heating reduction is 1100-1150 ℃.

Preferably, the microwave heating reduction uses a pushed slab kiln, the speed of the pushed slab kiln is 17mm/min, the constant temperature time is 60min, the temperature rise time is 253min, and the cooling time under the protective atmosphere is 277 min.

Preferably, the temperature after the water quenching is reduced to 900-1000 ℃.

Preferably, the water-quenched material is coarsely crushed and reselected before the ore grinding and dressing so that the water-quenched material is crushed to be less than-5 mm.

Preferably, the ore grinding granularity of the ore grinding process is-200 meshes and is more than 80%.

The invention has the beneficial effects that:

1. according to the invention, vanadium-titanium-iron ore concentrate, a reducing agent, a catalyst and a binder are uniformly mixed and then are subjected to microwave heating reduction, the microwave heating energy utilization rate is at least 25% higher than that of combustion heat supply, the reduction energy consumption of a unit product is reduced by more than 20%, the microwave heating is volume heating, the temperature is raised inside and outside, the temperature is raised quickly, the temperature is uniform, the reduction temperature is low, the reduction is complete, the metallization rate is favorably improved, even if vanadium-titanium magnetite which is a complex paragenetic ore difficult to reduce is reduced, the reduction period is saved by more than 14 hours compared with a domestic tunnel kiln, and the yield and the equipment utilization rate are greatly improved; the traditional combustion heating is replaced, so that the flue gas emission can be greatly reduced, the waste gas treatment capacity is reduced, the investment of environment-friendly equipment and the operation energy consumption are reduced, and the clean production is favorably realized; the subsequent water quenching treatment is combined, so that the grindability of the product is improved, the effective separation of iron and titanium components from the vanadium-titanium-iron concentrate after ore grinding and mineral separation is facilitated, and the metallization rate is improved.

2. According to the invention, the raw materials are weighed and mixed, then the briquetting treatment is carried out, the honeycomb-shaped briquette is formed, when the subsequent microwave heating reduction is carried out, the heated material has better wave absorption and refraction properties, the heated material obtains uniform microwave radiation, the outer surface area of the honeycomb-shaped material is large, the gaps of the material blocks are large, the wave absorption is favorably and uniformly heated, the inner pores increase the surface area, the microwave radiation and refraction heating are favorably realized, the gas generated by the reduction is favorably escaped, and the uniform heating is realized.

3. The method selects the vanadium-titanium-iron concentrate with the highest iron content at present in the Panxi area as the iron-containing raw material, obtains the highest metallization rate for reduction as much as possible, prepares high-grade primary iron powder, and simultaneously reduces the influence of gangue content on a byproduct, namely a vanadium-rich titanium material; the microwave heating ore block is heated by volume, the temperature is increased inside and outside together, the temperature is increased quickly and is uniform, molecules in the ore generate heat by high-speed friction due to microwave radiation, the wave absorption of the iron-containing ore is superior to that of gangue ore, and the iron-containing ore expands after being heated, so the microwave heating ore block is particularly suitable for climbing complex intergrown ores such as vanadium-titanium magnetite; by adopting the vanadium-titanium-iron ore concentrate as a raw material to produce primary and even secondary iron powder and simultaneously producing a vanadium-titanium-rich material as a byproduct, the resource utilization rate and the added value are improved, the price of the raw material is lower than 50% of that of imported ore concentrate, and preliminary measurement and calculation show that 200-400 yuan benefit can be generated by processing one ton of raw material briquettes to the primary iron powder; the secondary iron powder can generate 500-1000 yuan benefit.

4. The vanadium-titanium-iron ore concentrate is limited to have the granularity of-200 meshes, the percentage content of the granularity of-200 meshes accounts for more than 80% of the total mass, the percentage content of the granularity of the reducing agent accounts for more than 60% of the total mass, and the two raw materials have enough granularity, so that the reduction can be finished in a short time, and the subsequent ore grinding-ore dressing separation is facilitated. The invention selects the coal powder with high fixed carbon content as the reducing agent to reduce the coal powder material and reduce the influence of the coal powder ash on the vanadium-rich titanium material, and the coal consumption can achieve better reduction effect when the carbon surplus coefficient of the reduction reaction is 1.10-1.15.

5. The binder selected by the invention is corn starch, the addition of the binder can effectively increase the strength of the raw material or the briquettes, the raw material (especially the briquettes) with the improved strength can further improve the wave absorption and refraction of the raw material, so that the raw material can obtain uniform microwave radiation, and meanwhile, in order to prevent the pollution of the binder residues to the reduced material, reduce the effective content of the vanadium-rich titanium material and increase the content of harmful elements, the non-residual corn starch is used as the binder, and the proportion of the binder can be obviously reduced.

6. The invention limits the raw materials to be, vanadium-titanium-iron ore concentrate by mass percent: reducing agent: catalyst: binder (76.0-79.5): (16-19): (2.1-4.5) and (0.8-0.9), determining the proportion of the reducing agent and the catalyst according to the iron content of the vanadium titano-magnetite, wherein the iron oxide content is high when the iron content is high, the proportion of the required reducing agent and the catalyst is high, otherwise, the proportion of the adhesive is basically fixed, and on the premise of ensuring the strength of the briquette, the proportion is reduced as much as possible to reduce the cost. In the invention, the catalyst is a mixture of sodium sulfate and sodium chloride, the requirement of improving the metallization rate of the reduced product can be met when the mass percent of the catalyst is 2.1-4.5%, and the effect is limited when the proportion of the catalyst is continuously improved.

7. The temperature of the microwave heating is 1080-1300 ℃, the pushed slab kiln is used for the microwave heating, the pushed slab speed of the pushed slab kiln is 17mm/min, the constant temperature time is 60min, the temperature rise time is 253min, and the cooling time is 277min, namely 590min is counted from feeding to discharging, about 10 hours is about, 14 hours is reduced compared with the domestic current tunnel kiln reduction process, the test energy consumption (not counting protective nitrogen and equipment cooling water) reaches 800 kwh/ton briquetting through accounting, about 20 percent is saved compared with the traditional heating mode, and the result is that the reduction energy consumption is further reduced when the pushed slab kiln is produced in a large industrial production manner.

8. The water quenching process is rapid water quenching cooling at the temperature of 900-1000 ℃, the briquettes can be loosened, the water quenching sample is easy to grind, and the metal iron and TiO are₂And the like are easy to select, the ore grinding time is reduced, the ore grinding power consumption is reduced, the length of the pushed slab kiln can be shortened, the yield is further improved, but nitrogen protection cooling is still adopted due to equipment limitation in a 400 kg-grade expansion test, and the reduction effect of the expansion test is higher than that of the expectation, the metallization rate reaches 94%, so that the iron powder TFe after ore grinding and ore dressing also meets the requirement and reaches 96.5%.

9. The water quenched material is coarsely crushed and reselected before ore grinding and ore dressing, so that the water quenched material is crushed to be less than-5 mm. Because the residual carbon exists in the pressing block, the water quenching pressing block is firstly crushed to be below-5 mm through rough crushing, then the carbon powder with lighter weight and partial impurities are removed through reselection, the residual carbon is reduced to enter an ore grinding process, the carbon powder is prevented from forming a graphite film on the surface of metal iron, the grade of the iron powder is reduced, the heavy-weight material is separately subjected to magnetic separation, the grade of the iron powder can be effectively improved, the ore grinding granularity is controlled to be more than-200 meshes and more than 80 percent, the magnetic separation requirement can be met, and the iron and titanium separation effect is good.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a schematic representation of a microwave source and galvanic couple arrangement of the present invention;

FIG. 3 is a distribution diagram of the temperature in the kiln of the microwave heating pushed slab kiln;

fig. 4 is a flow chart of ore grinding-dressing.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to the following embodiments.

The microwave heating is introduced into the field of direct reduction, and is based on the large-scale, high-temperature and intelligent microwave heating equipment, the energy utilization rate (40-45%) of the microwave heating reduction adopted by the invention is far higher than that (15%) of combustion heating, so that the production cost can be reduced, the microwave heating ore blocks are subjected to volume heating, the temperature is increased inside and outside, the temperature is increased quickly, and the temperature is uniform; and combustion heat supply in the prior art is cancelled, so that the smoke emission is greatly reduced, and the smoke mainly comes from reductionGas phase (CO, CO)₂、H₂O) and reducing agents, reducing the rear flue gas treatment (dust removal, desulfurization, etc.).

In the invention, the vanadium-titanium-iron ore concentrate, the reducing agent, the catalyst and the binder can be uniformly mixed and then briquetted. The specific process of briquetting treatment is as follows: pressing the honeycomb briquette into briquettes with the shape of honeycomb briquette by using a briquetting machine, wherein the height of each briquette is 65mm, the diameter of each briquette is 90mm, 9 through holes with the diameter of 10mm are arranged, each briquette is 710-720 g in weight, and the briquettes are dried by exposure to the sun for 3 days so that the moisture content is less than 0.8%. The raw material mixing and the briquetting are all universal equipment, and the raw material mixing and the briquetting are uniformly mixed with water and dried. The microwave heating is characterized in that the material to be heated has better wave absorption and refraction, so that the material to be heated can obtain uniform microwave radiation, therefore, the blocky material is superior to the powdery material, and the honeycomb briquette is superior to the spherical material, because the outer surface area of the honeycomb material is large, the gaps between the briquettes are large, the wave absorption can be favorably and uniformly heated, the inner pores can increase the surface area, the microwave radiation and refraction heating can be favorably realized, the gas generated by reduction can be favorably escaped, and the uniform heating can be realized.

The vanadium titano-magnetite in Panxi area has rich reserves and is complex paragenetic ore of iron, vanadium and titanium, but TFe and V₂O₅、TiO₂The grade of the raw materials is 4-6% lower than that of other domestic manufacturers, and vanadium and titanium cannot be extracted as separate minerals and only can be subjected to a treatment process of relative enrichment recovery. The invention is based on abundant vanadium-titanium magnetite resources in the Panxi area, uses the prior high-grade vanadium-titanium-iron ore concentrate which has stable source and much lower price than imported ore concentrate, and separates out vanadium-titanium-rich materials while preparing primary iron powder by microwave heating and carbon reduction. The vanadium-titanium-iron ore concentrate comprises the following components in percentage by mass: 50% -60% of TFe, 18-28% of FeO and TiO₂ 9.5～20％，V₂O₅ 0.5～0.8％，CaO 0.4～1.5％，SiO₂ 3.5～5.5％，MgO 0.6～4.0％，Al₂O₃1.0-5.0% of S, 0.5-1.2%. Further, the vanadium-titanium-iron ore concentrate comprises the following components in percentage by mass: TFe 59.50%, FeO 24.90%, TiO₂ 9.60％，V₂O₅ 0.69％，CaO 0.41％，SiO₂4.11％，MgO 0.84％，Al₂O₃1.23% and S0.75%. The vanadium-titanium-iron ore concentrate is vanadium-titanium magnetite in Panxi area, the vanadium-titanium-iron ore concentrate with high iron content in Panxi area is selected as the iron-containing raw material, the metallization rate is obtained as high as possible for reduction, high-grade primary iron powder is prepared, and the influence of gangue content on a byproduct, namely a vanadium-rich titanium material, is reduced; the microwave heating ore block is volume heating, the temperature is increased inside and outside together, the temperature is increased quickly and is uniform, molecules in the ore generate heat through high-speed friction due to microwave radiation, the wave absorption of the iron-containing ore is superior to that of gangue ore, and the iron-containing ore expands after being heated, so that the microwave heating ore block is particularly suitable for climbing complex intergrown ores such as vanadium-titanium magnetite.

In the invention, the coal dust reducing agent adopts high carbon-containing anthracite, has the characteristics of high fixed carbon, low ash content, low volatilization and low sulfur, and comprises the following components in percentage by mass: 85.15% of C, 7.08% of A, 7.47% of V and 0.27% of S. The coal powder with high fixed carbon content is selected as the reducing agent so as to reduce the material consumption of the coal powder and simultaneously reduce the influence of the ash content of the coal powder on the vanadium-rich titanium material, and the use amount of the coal can achieve a better reduction effect when the carbon surplus coefficient of the reduction reaction is 1.10-1.15.

In the invention, the percentage content of the vanadium-titanium-iron ore concentrate with the granularity of-200 meshes accounts for more than 80% of the total mass, and the percentage content of the pulverized coal with the granularity of-200 meshes accounts for more than 60% of the total mass. The two raw materials must have sufficient particle sizes to ensure that the reduction is completed in a short time and to facilitate the subsequent ore grinding-dressing separation.

According to the invention, corn starch is used as a binder, the strength of the raw material or the briquetting can be effectively increased by adding the binder, the wave absorption and refraction of the raw material or the briquetting after the strength is improved can be further improved, so that the raw material or the briquetting can obtain more uniform microwave radiation, and meanwhile, in order to prevent the pollution of the binder residues to the reduced material, reduce the effective content of the vanadium-rich titanium material and increase the content of harmful elements, the non-residual corn starch is used as the binder, and the proportion of the binder can be remarkably reduced.

In the invention, the ratio of the raw materials is, by mass percent, vanadium-titanium-iron ore concentrate: reducing agent: catalyst: binder (76.0-79.5): (16-19): (2.1-4.5): (0.8-0.9), further, the mixture ratio of the raw materials is, by mass percent, vanadium-titanium-iron ore concentrate: coal powder: sodium sulfate: sodium chloride: corn starch ═ 76.0-79.5: (16-19): (1.0-2.3): (1.1-2.2): (0.8-0.9). The proportion of the reducing agent and the catalyst is determined according to the iron content of the vanadium titano-magnetite, the iron oxide content is high when the iron content is high, the proportion of the required reducing agent and the catalyst is high, otherwise, the proportion of the adhesive is basically fixed, and the proportion is reduced as much as possible to reduce the cost on the premise of ensuring the strength of the briquette. In the invention, the catalyst is a mixture of sodium sulfate and sodium chloride, the requirement of improving the metallization rate of the reduced product can be met when the mass percent of the catalyst is 2.1-4.5%, and the effect is limited when the proportion of the catalyst is continuously improved.

In the invention, the improved 2450MHz microwave source is adopted, which has the characteristics of adjustable power and longer service life. The working life of the microwave source is prolonged to more than 5000 hours from the past 1000-2000 hours, so that the microwave source can be applied to industry at ease, the shutdown maintenance time is reduced, the yield can be improved, the power of each microwave source can be independently adjusted, the uniform and controllable temperature distribution in the kiln is ensured, and the automation degree is higher.

The microwave heating temperature is 1080-1300 ℃, the microwave heating uses a pushed slab kiln, the speed of a pushed slab of the pushed slab kiln is 17mm/min, the constant temperature time is 60min, the temperature rise time is 253min, and the cooling time is 277 min. The total time from feeding to discharging is 590min, about 10 hours, which is reduced by more than 14 hours compared with the domestic current tunnel kiln reduction process, as shown in figure 3, the test energy consumption (without protection nitrogen and equipment cooling water) reaches 800 kwh/ton briquetting through accounting, about 20 percent of energy is saved compared with the traditional heating mode, which is the result on a small test kiln, and the reduction energy consumption is further reduced when a large industrial production push plate kiln is produced. In a laboratory test, a plurality of sets of tests are carried out on the reduction temperature, the test is carried out from high temperature to low temperature, and finally the contradiction between the reduction temperature and the reduction time is balanced and a lower reduction temperature is selected, so that the reduction of energy consumption and the maintenance cost of equipment are facilitated, and further, the temperature of the selected microwave heating is 1100-1150 ℃.

In the invention, the temperature is reduced to 900-1000 ℃ after the water quenching. A laboratory kilogram-level test is carried out for respectively carrying out oxygen isolation natural cooling and rapid water quenching cooling on a reduction product to 900-1000 ℃, and the result shows that the TFe of a water quenched sample is higher by 2-3% in the same grinding time of 180 seconds, which indicates that the water quenched sample is easy to grind, and metal iron and TiO are easy to grind₂And the like are easy to select. However, in the 400 kg-grade expansion test, nitrogen protection cooling is still adopted due to equipment limitation, and because the reduction effect of the expansion test is higher than the expectation and the metallization rate reaches 94%, the iron powder TFe after ore grinding and ore dressing also meets the requirement and reaches 96.5%.

In the invention, the water-quenched material is coarsely crushed and reselected before the grinding and ore dressing so that the water-quenched material is crushed to be less than-5 mm. Because residual carbon exists in the briquettes, the water quenching briquettes are firstly crushed to be below-5 mm through rough crushing, and then carbon powder with lighter weight and partial impurities are removed through gravity separation, so that the residual carbon is reduced to enter an ore grinding process, and the carbon powder is prevented from forming a graphite film on the surface of metal iron to cause the grade reduction of the iron powder. The heavy-weight separated light materials are separately magnetically separated, so that the grade of the iron powder can be effectively improved. The magnetic separation requirement can be met by controlling the ore grinding granularity to be more than 80 percent of minus 200 meshes, and the iron and titanium separation effect is good. See the grinding-dressing flow chart 4 in detail.

The foregoing is a detailed description of the invention and the following is an example of the invention.

Example 1

The flow chart of the present invention is shown in fig. 1.

Selecting raw materials:

vanadium-titanium-iron ore concentrate: the composition of the vanadium-titanium-iron concentrate used in this example is shown in table 1:

table 1 composition of vanadium-titanium-iron concentrate (mass fraction,%)

TFe	FeO	TiO₂	V₂O₅	CaO	SiO+	MgO	Al₂O₃	S
									59.50	24.90	9.60	0.69	0.41	4.11	0.84	1.23	0.75

The concentrate is a product which is improved in the mineral dressing level in recent years, is mainly used for producing high-grade pelletizing ore by steel enterprises at other places, but has lower yield and is hardly used by local steel enterprises; the granularity of the concentrate is finer than that of other grades of vanadium-titanium-iron concentrate, the-200-mesh size fraction reaches more than 80 percent, and the concentrate can be directly used without grinding.

Reducing agent: the coal dust (high carbon-containing anthracite) needs to be finely ground before use, so that the-200-mesh particle size reaches more than 50%, and the components of the coal dust used in the embodiment are shown in table 2:

table 2 pulverized coal composition (mass fraction,%)

C	A	V	S
				85.15	7.08	7.47	0.27

Catalyst: the chemical sodium sulfate and sodium chloride have the purity of over 99 percent.

Adhesive agent: corn starch.

The distribution ratio of the vanadium-titanium-iron concentrate, the reducing agent, the catalyst and the binder is shown in the following table 3:

table 3 raw material ratio (mass fraction,%), on a dry basis

Iron ore concentrate	Pulverized coal	Sodium sulfate	Sodium chloride	Corn starch
					76.0～79.5	16～19	1.0～2.3	1.1～2.2	0.8～0.9

Preparing raw materials:

weighing and batching the raw materials according to the proportion after moisture measurement, fully mixing the raw materials by a stirrer, adding a proper amount of moisture, and pressing the mixture into briquettes in the shape of honeycomb briquette by a briquetting machine, wherein the height of each briquette is 65mm, the diameter of each briquette is 90mm, 9 through holes with the diameter of 10mm are arranged, and each briquette is 710-720 g in weight. The pressed block is dried in the area of the Panzhihua by insolation for 3 days, and the measured moisture before entering the kiln is less than 0.8 percent.

Microwave heating reduction:

selecting microwave heating equipment:

the method is characterized in that a bench test of ten months is firstly carried out in a 5KW microwave oven in a laboratory, 4 1.25KW microwave sources provide heat sources, the highest working temperature is 1300 ℃, only one sample briquette can be tested in each test, the microwave sources do not have power regulation performance and can only carry out temperature control in an on-off mode, and the influence of parameters such as the proportion, granularity, heating speed, reduction temperature, reduction time, cooling mode and the like of all raw materials on the metallization rate of a reduced product is discovered on the equipment to form primary process parameters.

The scale-up test was carried out on a microwave-heated pusher kiln from science and technology, Inc. in Hunan, the equipment briefly described below:

the kiln temperature of the microwave heating pushed slab kiln can reach 1300 ℃ at most, 24 microwave sources with the power of 1.5KW are used as heating sources, and the 24 microwave sources are arranged on the two sides and the top of a kiln body. The frequency of the microwave source is 2450MHz, the microwave source is of an adjustable power type, namely the microwave source is used for controlling the temperature rise speed and temperature distribution in the kiln, the working power of the microwave source in each section can be adjusted, and the adjustable range of the power of the microwave source is 0.2-1.5 KW. The improved 2450MHz microwave source has adjustable power and long service life. The service life of the device is prolonged to more than 5000 hours from the past 1000-2000 hours, so that the device can be safely applied in industry, the shutdown overhaul time is shortened, and the yield can be improved. The power of each microwave source can be independently adjusted, so that the temperature distribution in the kiln is uniform and controllable, and the automation degree is higher.

The total length of the pushed slab kiln is 9600mm, wherein the feeding section is 2000mm, the heating section is 3600mm, the discharging cooling section is 4000mm, the cross section of the hearth is 180 mm in width and 110mm in height, the microwave source and the galvanic couple are arranged as shown in figure 2, and the scale is 1: 50. The loading push plate used in the embodiment is a magnesium-aluminum flat plate, the weight is 2000g, the size is 170 multiplied by 35mm, and bosses with the height of 2mm and the width of 6mm are arranged on the periphery of the loading push plate to prevent the material block from sliding out; the pushing speed of the pusher kiln is 1 plate/3 min at the fastest speed, namely 56.7mm/min, and is 1 plate/12 min at the slowest speed, namely 14.2mm/min, the pusher speed is reduced by an integer of minutes, and the feeding, discharging and unloading are completely manually carried out; a double-layer pneumatic gate valve is arranged at the tail of the kiln head and the kiln tail, so that air is isolated during feeding and discharging; bottled high-pressure N for pushed slab kiln₂And 6 air outlets are arranged on the upper surface of the kiln body, the inner diameter of each air outlet pipe is 25mm, and only one air outlet of the feeding section is opened in the test.

Microwave heating reduction process:

in the embodiment, a reduction test is carried out on a 400kg raw material briquette (560 briquettes), wherein the main technical parameters are that the reduction temperature is 1100 ℃ (the fluctuation range is 1095-1105 ℃), the constant temperature time is 60min when the speed of a push plate is 17mm/min, the temperature rise time is 253min, and the cooling time is 277 min. The total time from feeding to discharging is 590min, about 10 hours, which is reduced by more than 14 hours compared with the domestic current reduction process of the tunnel kiln, and the temperature distribution in the microwave heating pushed slab kiln is shown in table 4 and detailed in figure 3.

TABLE 4 temperature distribution in pushed slab kiln heated by microwave

The experimental energy consumption (not counting protective nitrogen and equipment cooling water) reaches 800 kwh/ton of briquetting through accounting, and the energy is saved by about 20 percent compared with the traditional heating mode, which is the result on a small-sized experimental kiln, and the reduction energy consumption is further reduced when a large-sized industrial production push plate kiln is produced.

Water quenching:and rapidly quenching and cooling the microwave heating reduction product at the temperature of 900-1000 ℃ to obtain a water-quenched briquette.

Grinding and dressing:because the residual carbon exists in the briquettes, the briquettes after water quenching are crushed to be below-5 mm through rough crushing, and then carbon powder with lighter weight and partial impurities are removed through gravity separation, so that the residual carbon is reduced to enter an ore grinding process, and the carbon powder is prevented from forming a graphite film on the surface of metal iron to cause the reduction of the grade of the iron powder; the heavy-weight separated light materials are separately subjected to magnetic separation, so that the grade of iron powder can be effectively improved; the magnetic separation requirement can be met by controlling the ore grinding granularity to be-200 meshes and be more than 80%, and the iron and titanium separation effect is good, which is detailed in an ore grinding-ore dressing flow chart 4.

Example 2

The same as example 1 except that 400kg of raw material briquettes among the microwave heating reduction parameters were replaced with 1kg of raw material briquettes, and the reduction temperature was 1150 ℃.

Example 3

The only difference from example 1 is that the microwave heating reduction temperature is 1080 ℃.

Example 4

The only difference from example 1 is that the reduction temperature was 1300 ℃ by microwave heating.

Example 5

Carbon reduction effect by microwave heating

The microwave heating carbon reduction results of example 1 and example 2 are shown in table 5:

TABLE 5 microwave heating of carbon reduction results

Note: the ore dressing loss is 1-3%, the loss is not considered in the calculation data in the table, and eta is the metallization rate.

As can be seen from Table 1, the metallization ratio of the invention can meet the requirements, and on the premise of a certain carbon blending amount and raw material granularity, the metallization ratio can be improved by continuously increasing the temperature or the reduction time, but the effect is limited. Because the vanadium-titanium-iron ore concentrate belongs to complex paragenic ore, the direct reduction metallization rate of more than 95 percent can not be obtained like imported ore concentrate, and the ore dressing result shows that the satisfactory iron powder index can be obtained when the metallization rate eta reaches more than 93 percent.

Example 6

Water quenching effect

In a laboratory kilogram-level test, a comparative test of oxygen-isolated natural cooling and rapid water quenching cooling of a reduction product to 900-1000 ℃ is respectively carried out.

The comparison shows that the TFe component of the iron powder of the water-quenched sample is higher by 2-3% and reaches 96.78% when the same ore grinding time is 180 seconds, which indicates that the metal iron and TiO of the water-quenched sample are₂And the like are easier to select, and meanwhile, the grinding time under the water quenching condition is shorter when the same TFe component content is required, so that the water quenching sample is easier to grind.

But in the 400kg scale-up test, nitrogen protection cooling is still adopted due to equipment limitation. Because the reduction effect of the expansion test is higher than the expectation, the metallization rate is close to 94%, so the iron powder TFe after grinding and mineral separation also meets the requirement, and reaches 96.5%.

Example 7

Grinding-dressing effect

The water-quenched compacts of examples 1 and 2 were subjected to 10 kg-grade ore grinding-dressing tests, and the results of the two tests are shown in tables 6 and 7.

TABLE 6 Ore grinding-dressing index

TABLE 7 recovery of each beneficial element (mass fraction,%)

Note: the ore dressing loss is 1-3%, and the loss is not considered in the calculation data in the table.

In order to prevent the residual carbon in the water quenching briquette from forming a carbon film to wrap metal iron particles in ore grinding and reduce the total iron content of the iron powder, a process of gravity separation is added particularly after a coarse crushing section, so that the residual carbon and other light impurities can be effectively separated and the grade of the iron powder is improved.

Table 6 shows that the primary reduced iron powder with total iron greater than 95% can be obtained from the water quenched briquettes through a simple ore grinding-ore dressing process, the iron powder can be sold to secondary iron powder production plants as a primary product and can be used as a raw material to obtain metal iron powder with total iron of more than 98% through secondary hydrogen reduction annealing, and the key point is that the iron powder is a microalloyed product due to natural small amount of vanadium and titanium, and the iron powder is beneficial to improving the performance of a subsequently manufactured iron-based product.

From table 7, it can be seen that under the condition that the raw material concentrate grade is 60%, the recovery rate of iron reaches 88%, the resource utilization requirement is met, meanwhile, vanadium and titanium are recovered from tailings, the recovery rate is higher than that of other conventional beneficiation processes, and the vanadium-titanium-rich material can be used for further extracting vanadium-titanium resources through hydrometallurgy.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims

1. The preparation method of the iron powder and the vanadium-rich titanium material is characterized by comprising the following steps:

2. The method for preparing iron powder and vanadium-rich titanium materials according to claim 1, wherein the vanadium-titanium-iron concentrate is mixed with a reducing agent, a catalyst and a binder, and then briquetted and dried.

3. The method for preparing the iron powder and the vanadium-rich titanium material according to claim 1, wherein the vanadium-titanium-iron concentrate comprises the following components in percentage by mass: 50% -60% of TFe, 18-28% of FeO and TiO₂ 9.5～20％，V₂O₅ 0.5～0.8％，CaO 0.4～1.5％，SiO₂ 3.5～5.5％，MgO 0.6～4.0％，Al₂O₃ 1.0～5.0％，S 0.5～1.2％。

4. The method for preparing iron powder and vanadium-rich titanium materials according to claim 1, wherein the percentage content of the vanadium-titanium-iron ore concentrate with the particle size of-200 meshes accounts for more than 80% of the total mass.

5. The method for preparing iron powder and vanadium-rich titanium material according to claim 1, wherein the percentage content of the reducing agent with a particle size of-200 meshes accounts for more than 60% of the total mass.

6. The method for preparing iron powder and vanadium-rich titanium material as claimed in claim 1 or 2, wherein the binder is corn starch.

7. The method for preparing iron powder and vanadium-rich titanium materials according to claim 1, wherein the raw materials comprise, by mass percent, vanadium-titanium-iron concentrate: reducing agent: catalyst: binder (76.0-79.5): (16-19): (2.1-4.5):(0.8-0.9).

8. The method as claimed in claim 1, wherein the temperature of microwave heating reduction is 1080-.

9. The method for preparing iron powder and vanadium-rich titanium materials according to claim 1, wherein the microwave heating reduction uses a pushed slab kiln, the speed of the pushed slab kiln is 17mm/min, the constant temperature time is 60min, the temperature rise time is 253min, and the cooling time under protective atmosphere is 277 min.

10. The method for preparing iron powder and vanadium-rich titanium material as claimed in claim 1, wherein the temperature after water quenching is reduced to 900-1000 ℃.